Objectives. The purpose of this study was to examine the roles of green tea drinking, and their possible joint effects with alcohol drinking and tobacco smoking and polymorphism of susceptibility genes on the risk of three Upper-GI cancers. Methods. A population-based case-control study was conducted in Taixing, China, including 206, 204, 218 newly diagnosed cases with stomach cancer, liver cancer, esophageal cancer and 415 shared healthy control subjects. Epidemiological data were collected by in-person interview using a standard questionnaire. Polymorphisms of susceptibility genes (include GSTM1, GSTT1, GSTP1, P53 codon 72) were assayed by PCR-RFLP techniques. A multigenetic index was created by summing up the number of risk genotypes. The data were analyzed using the logistic regression model. Results. A reverse association between green tea drinking and risk of stomach cancer was observed with an adjusted OR of 0.59 (95% CI: 0.34-1.01). Dose-response relationship was observed (P trends <0.05). For individuals who drink green tea more than 250g per month, the risk might be reduced about 60%. Though a slightly decreased risk of liver cancer was also found with the higher consumption of green tea, the trend is not significant. The present study didn’t observe independent relationship between green tea drinking and esophageal cancer. In addition, green tea drinking may decrease 81%, 78%, 39% risk for developing to stomach, liver and esophageal cancer among alcohol drinkers and also may decrease 16%, 43%, 31% risk of three cancers among cigarette smokers. Green tea was suggested to have significant more than multiplicative interactions with alcohol consumption for stomach and liver cancer with ORs for interaction of 4.57(95%CI: 1.62∼12.89), 4.36(95%CI: 1.75∼10.87) respectively. A higher score on the multigenetic index was associated with increased risk of stomach cancer, with an adjusted OR of 2.21 (95%CI: 1.02-4.79) for those with at least three risk genotypes compared to those with less than two risk genotypes. Possible more than multiplicative interaction between higher multigenetic index and green tea drinking was also shown with adjusted OR for interaction of 2.31 (95%CI: 0.88-6.03) for stomach cancer. Conclusion. In this study, the protective effect of green tea drinking and its interaction with alcohol drinking was observed on the risk of stomach cancer and liver cancer, the possible effect modification of susceptibility genes on stomach cancer was suggested.

[Proc Amer Assoc Cancer Res, Volume 47, 2006]